Can your iPhone monitor HR and cadence?

Aside from that my phone wouldn't last with the screen on for a 5 hour ride. I also don't feel comfortable mounting my $500 phone to my handlebars. I have looked - very hard - for a handlebar mount for my phone but there just isn't a solution that I love. They either require zip ties or rubber bands to ensure it won't pop off if I go over a pot hole or it's in a sealed case making it difficult to operate the touch screen and connect headphones to it.

Ultimately though it comes down to battery life. I don't think my phone is as accurate as my Garmin and to top it all off I don't think there is a better data analysis solution than Garmin Connect.